Optimistic vs ZK Rollups: Upgrade Control

Multi-sig or DAO-controlled upgrades: Protocols like Arbitrum and Optimism use a centralized Security Council or DAO vote to deploy new logic contracts, enabling rapid feature deployment and bug fixes without user action.

Key Advantage: Allows for swift responses to vulnerabilities (e.g., the Optimism Bedrock migration) and iterative protocol improvements. This is critical for fast-moving DeFi ecosystems like Uniswap or Aave that require new opcodes or precompiles.

Trade-off: Introduces upgradeability risk. Users must trust the governance model, as a malicious upgrade could freeze or drain funds.

Built-in escape hatch: The fraud proof window (typically 7 days) provides a safety net. Even during a malicious upgrade, users have time to force-withdraw assets via the L1 escape hatch contract.

Key Advantage: This creates a credible threat against governance attacks, as capital can flee. It's a non-negotiable feature for institutional custodians or protocols managing high TVL (e.g., over $10B on Arbitrum).

Trade-off: Exit mechanics are complex and require active monitoring, creating a poor UX during crises compared to ZKR's instant finality.

Upgrades require a new verifier: ZKRs like zkSync Era, Starknet, and Polygon zkEVM have their security rooted in a single verifier contract on L1. Changing circuit logic necessitates deploying and trusting a new verifier.

Key Advantage: Stronger security guarantees. Once a proof is verified on L1, state transitions are immutable. There is no "governance override" for already-finalized blocks. This is ideal for sovereign chains or assets requiring maximal censorship resistance.

Trade-off: Upgrades are slower and more cumbersome. Migrating users to a new verifier requires significant coordination, potentially fragmenting liquidity.

Prover network decoupling: The prover (entity generating validity proofs) can be upgraded or replaced independently of the on-chain verifier, as long as proofs adhere to the circuit.

Key Advantage: Enables performance upgrades (e.g., moving from CPU to GPU provers) and new proof systems (e.g., Starknet's shift to STARKs) without a hard fork. This fosters innovation in proof efficiency, directly reducing costs for users of dApps like zkSync Hyperchains.

Trade-off: Relies on a competitive prover market. If prover centralization occurs, it could lead to higher fees or censorship, though the L1 verifier remains the ultimate arbiter of truth.

Multi-week timelocks and DAO votes: Upgrades (e.g., on Arbitrum or Optimism) are typically proposed and executed through their respective DAOs (Arbitrum DAO, Optimism Collective). This involves a 7+ day voting period followed by a 10+ day timelock before execution. This matters for protocols requiring maximum credible neutrality and censorship resistance, as no single entity can unilaterally change the rules.

Slower response to critical bugs: The lengthy governance process is a liability for emergency security patches. If a vulnerability is discovered in the sequencer or bridge, the protocol remains exposed until governance completes. This matters for high-value DeFi protocols (like Aave or Uniswap) where exploit risk during the delay window is unacceptable. The security model relies on the fraud proof window as the primary defense.

Developer-controlled upgrade keys: Most ZK-Rollups (e.g., zkSync Era, Starknet, Polygon zkEVM) currently use multi-sig wallets controlled by the core development team to upgrade bridge and prover contracts. This enables sub-24 hour patches for critical issues and rapid feature deployment. This matters for rapid iteration cycles and emergency responses, providing a similar agility model to early Ethereum L1 development.

Active trust in the developer team: Users must trust that the multi-sig key holders will not act maliciously or be compromised. A rogue upgrade could freeze funds or alter contract logic. This matters for institutional custody and long-term asset storage, where maximizing trust minimization is paramount. The trade-off is explicit: agility is purchased with increased centralization risk until decentralized provers and governance are implemented.